Apparatus for condensation and sublimation



APPARATUS FOR CONDENSATION AND SUBLIMATION R. J. SCHMIDT El'AL Oct. 7,1958 2 Sheets-Sheet 1 Filed Dec O t- 7, 1958 R. J. SCHMIDT ETAL2,855,281

APPARATUS FOR couoausmxou AND SUBLIMATION 2 Sheets-Sheet 2 Filed Dec.13, 1945 n I I I I I I u I INVENTORS. Baberz 7. 62/702263 BY Frank Fuzs,J:

,4 r roeMs'Y .4. l, in A United States Patent APPARATUS FOR CONDENSATIONAND SUBLIMATION Robert J. Schmidt and Frank Fuis, Jr., Oak Ridge, Tenn.,assignors, by mesne assignments, to the United States of America asrepresented by the United States Atomic Energy Commission ApplicationDecember 13, 1945, Serial No. 634,860

6 Claims. (Cl. 23-264) This invention relates to an apparatus for thecondensation of sublimed materials and to a process of condensation.More particularly this invention concerns a condensation apparatus and amethod of condensation adapted for the condensing of sublimed uraniumcompounds for obtaining improved crystalline structure of the condensedmaterial.

This invention constitutes an improvement in certain of the featuresdescribed in the copending application of Krohn et al.,' Ser. No.553,446, filed September 9, 1944, which matured into Patent No.2,743,168 on April 24, 1956, and in which one of the inventors in thiscompanion application is a co-inventor in the instant application. Asdescribed in said companion application, sublimation apparatus andprocesses have a number of uses in industry. In the copendingapplication a valuable apparatus and process is described for use inprocessing various uranium compounds. It is sufficient to point outherein that the copending application disclosed a structure forvolatilizing the compound under treatment and a condensing means whichincluded a liner and spiral bafile whereby the sublimed materials werecondensed in a special manner.

The particular improved construction described herein pertainsespecially to the condenser structure and process. Any suitablesublimation unit, such as that fully disclosed in said companionapplication, may be employed without change, as indicated in Fig. 4herein. We have discovered, as fully described hereinafter, aconstruction whereby sublimedvmaterials may be condensed under verycarefully controlled conditions to give an improved condensate. Also thecondensed materials may be conveniently removed from the apparatus bymeans of the demountable liner and baflle construction of the presentinvention thereby facilitating such sublimation operations.

This invention has for one object to provide an im proved sublimedmaterials condenser construction and process of condensation ofsublimate.

Still another object is to provide an improved sublimate condensationand process of condensation particularly applicable to the treatment ofuranium materials.

Another object is to provide a sublimed materials condenser constructionthat has improved characteristics from the standpoint of temperaturecontrol, speed of operation, and ease of disassembly.

A still further object is to provide a sublimed materials condenserconstruction containing certain demountable parts and adapted to a widerange of temperature control.

A still further object is to provide a sublimed materials condenser ofthe aforementioned class particularly useful in the formation of largehomogeneous crystals of the material being condensed.

Still another object is to provide a sublimed materials condenser of thetype described that is adapted to operating in conjunction with a vacuumsystem and certain other associate parts and which cooperates therewithin a manner that the entire setup is subjected to fewer operationalditliculties.

Another object is to provide a sublimed materials condenser constructionparticularly useful for condensing uranium halide vapors.

Still another object is to provide a process of condensation wherebycontrol of crystal size of the sublimate may be obtained.

Another object is to provide a sublimation process wherein either cold,warm, or a combination type of condensation of sublimate may beaccomplished.

Other objects will appear hereinafter.

We have found that suitable apparatus may be constructed for condensingsublimed materials comprising a condenser construction fitted with aremovable liner and a special demountable baffle attached to the liner.The baffle is preferably of a generally spiral shape and is providedwith a certain number of coils disposed within the surfaces of thebaffle, the circulation of the temperature controlling medium beingwithin the bafile. A special construction is also provided so that thecooling medium conduits may be disconnected. Also the entireconstruction is adapted to operate in a leak-proof manner under reducedpressure of a low order.

For a further understanding of our invention reference is made to theattached drawing forming a part of the present application.

Referring to the drawings,

Fig. l is a perspective view showing certain parts broken away and otherparts in section showing the baffle, the demountable construction andthe temperature controlling means.

Fig. 2 is a detailed view showing the demountable baffle holding means.

Fig. 3 is a detailed view, in section, of certain parts associated withthe conduits furnishing the temperature controlling fluid.

Fig. 4 is a sectional elevation of a suitable sublimation unit incombination with our improved condenser.

Referring to Fig. 1, reference numeral 2 represents the completecondenser assembly. The removable special baflie of the presentinvention is shown at 3. As in said companion application the condensercomprises an outer shell 4 and the removable inner liner 5. That is, byremoving the condenser head 6 access is had to closure 7 on the liner.These various closures are held in place by bolts as shown on thedrawing.

The liner 5 contains the convolute or spiral baflie 3 held therein bymeans of a demountable construction comprising the long pin 8 throughthe several brackets 9.

As better shown in Fig. 2, the brackets are made up of several parts,namely U-shaped member 11 provided with a rounded recess 12 for the pin8. This part 11 is welded or otherwise securely attached onto the baffle3. The other part, namely part 13 is welded or otherwise securelyfastened to the liner 5. A cross supported or reenforcing member 14 maybe provided for supplying rigidity to the baffie. As apparent from thedrawings the parts may be secured in place by the insertion of thetapered locking pin 8. A handle portion 16 on the pin provides a meansof applying leverage by which the pin may be loosened when it is desiredto disconnect the baflle from the liner.

Referring now to the bafiie construction, the baflle may be of adouble-walled construction containing a plurality of coils 17. In placeof coils the double-walled section' Patented Oct. 7, 1958 tail underFig. 3. While this header mechanism has been shown extending across theentire width of the baflle, the exact width of header 21 would begoverned by the number of coils 17 which the header is to supply andsimilar factors. Hence, the part 21 might only extend a part of the wayacross the baflle. I

This last-mentioned means 21 is associated with the various fittingsindicated overall by reference numeral 22 for providing vacuum tightinlet and outlet so that the conduits carrying temperature controllingfluid may be connected through the closures 6 and 7 to the baflle andfunction Without loss of vacuum due to leakage around this joint.

Referring to Fig. 3, the above-mentioned vacuum tight means comprises aplurality of concentric tubes 23 and 24 which lead into the coils 17 ofbaffle 3 through the several closures 6 and 7. One of these conduits maybe provided for introducing temperature controlling liquid and the otherfor withdrawing the liquid. The conduits are enclosed by a Wilson typeseal or other vacuum tight construction 25 (not an integral part of thepresent invention and the details of which, therefore, are omitted)which is held in place by the nut 26. For details respecting such typeof seal reference may be made to Review of Scientific Instruments, vol.12 (1941), pp. 9293. Other concentric conduit means 27 with associatedsealing nuts 28 and 29 are provided so that a leak proof connection maybe made to the conduit 23. By removing the various nuts 28 and 29, thevarious other parts may be removed so that the closures 6 and 7(including the Wilson seal) may be pulled 01f over conduits 23 and 24permitting access to the liner and the baffle 3. These latter parts maythen be removed, the spiral baffle being disassembled by means ofremoving pin 8 by turning handle 16.

As indicated, the construction described under Fig. 3 may include one ormore seals known as the Wilson seal and packing material or equivalentconstruction for preventing leakage around conduits 23 and 24 into theapparatus.

The operation of the apparatus is to a large extent similar to theoperation described in companion application of Krohn et al., supra. Itis sufiicient for the present invention to indicate that the sublimedmaterials enter the sublimed materials condenser at or about the singlewall construction designated 18. The vapors enter the interior portionof the baffle and move along the inner walls to the outer walls of thespiral and are condensed on such walls in the desired manner by the flowof the temperature controlling medium in the coils 17, since this has acooling effect upon the barrier Walls. The sublimate not condensed onthe interior of the spiral passes around to the outside of the spiral sothat the remainder is thereby condensed on the outer portions of thebaflle and on the liner. Any residual non-condensables leave theapparatus in a manner the same as described in said companionapplication, that is, through an exit duct which communicates withregistering openings in the outer shell and the condenser. In general,in the condensation process the improved condensation is obtained bycirculating a heated medium and changing the temperature of the mediumcirculated as the process progresses so that the temperature of thebaffle is maintained between about 300400 C. thereby giving improvedcrystal structure to the condensed product. By means of this arrangementa large input of sublimed materials may be handled by the spiralcondenser. At the conclusion of the process when the spiral condenserhas completed its function, the head 6 is removed by disconnecting thesealing mechanism shown in Fig. 3 and unbolting head 7 whereby readyaccess may be had to the interior of the apparatus. The spiral may thenbe readily removed by turning the release member 16 and the spiral takento a dry box for removing the condensate. Thereafter another demountablespiral and liner can be quickly inserted into the equipment and furtherprocessing carried out. In this connection, it will be understood thatany appropriate detachable connections, such as removable rubber hose,may be employed to join the lines 23, 24 to the source of heating orcooling fluid. In removing the baflle these connections are severed ordetached and the studs are removed from the flange of outer shell 4,releasing head 6 from the shell. At this point, the arrangement of innercasing 5, baflle 3, and head 7 may he slid out of the outer casing 4, orthe tee 27 and outer head 6 may be removed, and then the bolt securinghead 7 to inner casing 5 taken out. If the former procedure is followed,removal of tee 27 and head 6 may be delayed until after the casing andbaffie arrangement has been taken from the outer shell 4. In eitherevent separation of the casing 5 and the baflle 3 is finallyaccomplished by moving the tapered pin 16 outwardly to loosen it andpermit final disengagement of the parts 13 and 11 of the clamp, whichare normally keyed together by the proper positioning of the key 8. Oncethese clamping elements have been disengaged and tee 27 and thimble 26loosened, the baflle 3 may be readily slid out of casing 5.

In further detail one method of operation is to preheat the baflle tobetween 350 C.45() C. by the circulation of hot fluid in coils 17.Likewise heating fluid would be circulated in the coils external toshell 5. This preheating is accomplished prior to conducting the vaporsof sublimed materials into the apparatus. By such procedure thecondensation of FeCl' AlCl and other volatile impurities which tend tocome off first in sublimation processes and which have heretofore, inthe prior art, been condensed in the condenser while it was heating up,is prevented from doing so in the present arrangement, thereby giving apurer product.

While the sublimation processes of the present invention may be operatedat below 50 mm. pressure as described in the companion application ofKrohn et al., supra, it may also be operated at higher pressures andtemperatures. In other words, various temperature-pressure conditionsmay be used as long as liquid phase conditions are not involved. Theconditions should be such that the material under treatment should gofrom the solid phase to the vapor phase and then to condensation in thepresent apparatus. By being able to maintain the baflle and associatedparts at any desired temperature, the sublimation may be conducted athigher pressures and at a slower rate than heretofore. Such slowersublimation gives a purer product in that there is less entrainment orother carrying over of impurities.

Therefore it may be seen that there is considerable flexibility in theconstruction and operation of the present invention. For example inaddition to coils 17, electrical resistance heating elements may also beincluded for permitting a quicker preheating of the baffle. In place ofusing such usual heating fluids as steam, hot oil and the like, heattransfer mediums such as Dowtherm and the like may be circulated in thecoils.

Referring to Fig. 4, showing the condenser in combination with asublimation unit such as disclosed in the copending application of Krohnet al., supra, the outer shell of the condenser indicated at 4, has areduced tubular extension 32 for housing a trough or boat 30 which isadapted to receive sublimation materials. One end of the trough 30 isadapted to abut against the end wall 34 of the extension 32, while theopposite end of the trough abuts against the end of extension 18 of thebaffle 3, effectively limiting the flow of vapors from the materials ofthe trough 30 to a path extending into the interior of the bafile. Theliner 5 has an opening in an upper portion intermediate its ends whichis adapted to register with the outlet in shell 4 when the liner is inplace. This outlet takes the form of a tube 35 connected to a vacuumpump (not shown) or other exhaust system. The inner casing or liner hasa tubular projection 36 which telescopes within extension 32 of theshell and heated liquids or a cooling medium for controlling thetemperature of the casing. However, if desired, heat may be applied tothe casing through the use of calrod or other heating elements wrappedabout the outer surface of shell 4 in a manner similar to that disclosedin Fig. 1. Heat may be applied to the extension 32 of the shell by meansof an'electric furnace which telescopes thereover. A suitable form ofsuch furnace is disclosed in Krohn et al., supra.

In Fig. 4 the solid and dotted arrows indicate the general path whichthe gaseous vapors follow. These vapors leave the trough or boat 30 andenter the condenser 4 and baflle 3 through extension 18 of the bafilewhich tends to deflect the vapors, causing them to pass along into theinterior of the bafile. These vapors then travel along its interiorsurface to the edge of the baflle 3 and then travel back along the outersurface thereof to the exit duct or tube 35 for removal by the vacuumaction of the vacuum source (not known).

It is to be understood that all matters contained in the abovedescription and all examples given herein are illustrative only, and donot limit the scope of this invention, as it is intended to claim theinvention as broadly as possible in view of the prior art.

We claim:

1. A sublimation apparatus of the character described comprising acondenser housing, a removable liner disposed within the housing,registering openings in the walls of the housing and liner for removalof gases, a coiled baflle of spiral configuration positionedwithin,'having progressively large convolutions, and secured to theliner, the walls of said baflie providing condensing surfaces, means fordisengaging the bafile from the liner to permit removal, and means forleading gaseous vapors into the interior of said baffie for travelingover its condensing surfaces.

2. A sublimation apparatus of the character described comprising acondenser housing, a removable liner disposed within the housing,registering openings in the walls of the housing and liner for removalof gases, a spiral bafiie having progressively larger convolutions andwhose walls provide outer condensing surfaces, positioned within theliner, tubular members for the passage of a temperature control mediumdisposed within the walls of the baffle, and means for feeding gaseousvapors into the interior of the bafiie for contact with its condensingsurfaces.

3. A sublimation apparatus of the character described comprising acondenser housing, a removable liner disposed within the housing,registering openings in the housing and liner for the removal of gases,a curved baffle disposed within and removably secured to the liner,

coils disposed within the walls of the bafiie for the circulation of atemperature control medium, and means for leading gaseous vapors intocontact with the inner surfaces of said curved bafie.

4. A sublimation apparatus of the character described comprising anouter tubular housing, a removable liner disposed within the housing,registering openings in the housing and liner for removal of gases, acurved baffle disposed within said liner, means for removably securingsaid bafile to said liner including mating clamping elements joined tothe liner and the bafile and a key for interlocking them, and means forleading gaseous vapors into the interior of the battle for travel overthe exposed surfaces of said baffle.

5. A sublimation apparatus of the character described comprising anouter tubular housing, a removable liner disposed within the housing,registering openings in the liner and housing for the removal of gases,a spiral bafile having progressively larger convolutions and whose wallsprovide exposed surfaces disposed within the liner, means for removablysecuring the baffle to the liner including mating clamping elementssecured to the liner and bafile and having grooves therein for defininga key way, and a removable key for interlocking the clamping elements,tubing disposed within the walls of the bafile for the passage of atemperature control medium, and means for leading vapors into theinterior of said battle for contact with its exposed surfaces.

6. A sublimation apparatus of the character described comprising anouter tubular housing, a removable liner disposed within the housing,registering openings in the housing and liner for removal of uncondensedvapors, a spiral shaped bafile with spaced double walls defining aspiral chamber, and the outer exposed surfaces of said walls providinginterior and outer condensing surfaces, said baffle being disposedwithin the liner, means for removably securing the baffie to the liner,including mating clamping elements mounted on the liner and the baffleand having depressions therein for registration to define a key way anda removable key for seating in said key way to interlock said clampingelements, tubing disposed between the walls of the bafile for thepassage of a temperature control medium, means communicating with thetubing for supplying temperature control medium to and removing it fromsaid tubing, and means for feeding gases to be condensed into theinterior of the baffle for progressive travel over the interior andouter exposed surfaces thereof to said registering openings.

References Cited in the file of this patent UNITED STATES PATENTS1,434,485 DAdn'an Nov. 7, 1922 1,478,750 McElroy Dec. 25, 1923 1,833,664Vandegrift Nov. 24, 1931 1,956,133 Rosenblad Apr. 24, 1934 FOREIGNPATENTS 355,272 Great Britain Aug. 17, 1931 552,254 Great Britain Mar.30, 1943

1. A SUBLIMATION APPARATUS OF THE CHARACTER DESCRIBED COMPRISING ACONDENSER HOUSING, A REMOVABLE LINER DISPOSED WITHIN THE HOUSING,REGISTERING OPENINGS IN THE WALLS OF THE HOUSING AND LINER FOR REMOVALOF GASES, A COILED BAFFLE OF SPIRAL CONFIGURATIONS POSITIONED WITHIN,HAVING PROGRESSIVELY LARGE CONVOLUTIONS, AND SECURED TO THE LINER, THEWALLS OF SAID BAFFLE PROVIDING CONDENSING SURFACES, MEANS FORDISENGAGING THE BAFFLE FROM THE LINER TO PERMIT REMOVAL, AND MEANS FORLEADING GASEOUS VAPORS INTO THE INTERIOR OF SAID BAFFLE FOR TRAVELINGOVER ITS CONDENSING SURFACES.